(CNN) -- Dutch officials say a gunman opened fire at a mall on Saturday, killing seven people and wounding 16 others before shooting himself in the head, a journalist with CNN affiliate SBS reported, citing police and other officials.

Bas Eenhoorn, mayor of Alphen aan den Rijn, told reporters that the 24-year-old suspected shooter -- identified only as Tristan V -- fired an automatic rifle and killed himself before police arrived on the scene.

The suspect, whose full name is being withheld until a formal investigation is concluded, is a Dutch national who was living with his father, police told SBS. Computer equipment and other materials were confiscated from the father's apartment after the shooting.

A farewell note was found at the suspect's mother's home. Police told SBS that the suspect claimed in the note that he had placed explosives in several commercial areas in Alphen.

The areas were evacuated as police conducted a search. As of 11 p.m., no explosives were found.

Three of the wounded mall victims are in critical condition, officials said Saturday night. The motive of the shooting was not known and no indication was given in the note.

Eenhoorn plans to hold meetings Sunday with some of the victims, SBS reported.